Process for making fused multifocal lenses



Aug. 17 ,1926. y1,596,397

L.. W. BUGBEE, JR

PROCESS FOR4 MAKING FUSED MULTIFOGAL LENSES Filed Deo. 14. 1925 "121%l 1Fl. L* F13. E

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Patented Aug. 17, 1926.

UNITED STATESv lxrarrr OFFICE.

`LUCIA.N'W. BUGBEE, JR., 0F INDIANAPOLIS, INDIANA, ASSIGNOR, BY MESNEAS- SIGNMENTS, TO`CONTINENTAL OPTICAL CQRPORATION, F NEW YORK, N. Y., A.

' CORPORATION oF DELAWARE.

PROCESS FOB MAKING FUSED MULTIFOCAL'LENSES.

Application led December 14, 1925. Serial No. 75,357.

This invention relates to an improvement in the process of fusingmultifocallenseswherein the major element 1s made of glass which meltsor softens at a lower tempera.

ture t-han the glass which composes the minor element and in vwhichduring the fusino' process the major element is superimposed onl andcovers the minor element and sags down into a -fusing engagement withthe minor element so as to protect and cover the minor element and keepout dust and foreign particles from the two surfaces to be fused andexpels the air from -between the two 'surfaces as the fusing'takesplace.

The chief feature of this invention consists in supporting the majorelement in particular relation to\ the minor element on a block duringthe fusion of said elements in such manner as to facilitate theexpulsion of the air from between the surfaces being fused prior to theelement fusion.

The fullnature' o'f the invention will be understood from theaccompanying drawings and the following description and claims.

In the drawings, Fig. 1 is a plan view of the major element. Fig. 2 is aplan view of the minor element. Fig. 3 is a'central vertical crosssection throughw the elements and a block with which they are assembledpreliminary to fusion. Fig. 4 is the same after fusion. Fig. 5 is asimilar section of the fused blank. Fig. 6 is a similar section of thefinished lens. Fig. 7 isa similar section of a modified way of carryingout the process. Fig. 8 is a similar sectlon after fusion. Fig. 9 showsa modified form with parts arranged as in Fig. 3.

In the drawings there is shown a ma'or element. 10 which lis made ofglass which lmelts or softens at a lower temperaturethan the glassforming the minor element 11. The major element has a slight countersink12 formed therein to receive the minor element. The curvature of theminor element is carefullly and exactly made the samevas the desiredfnalcurvature so as to determine such final curvature of the fusedsurfaces in the finished lens. countersink 12 in the majorelement is notso carefully made and is preferably of less curvature than the curvatureof the minor ele'- ment.

Preliminary to fusion the elements are The curvature of thev assembledas sh'own in Fig. Srwherein there is a block 13 having a curvature thesame as the general curvature of the major element and it has a recess14 for seating the minor l .element as shown, so that the marginl of theminor element all round will be substantially flush with the surface 'ofthe'block.

Themajor element is superimposed on the block and minor element yasshown in Fig. 3

\ with the countersink over the minor element and in contact with thecentralpoint of theY minor element substantially, and the mar# gin ofthe major element which is remote rom the mlnor element, isl supportedby a wedge or piece 15, here shown triangular in cross section, mountedon the block 13 so as to` support the major element separated from thesurface of the block. The edfre ofthe major element rests on the Iapexof the wedge 15' preliminary to fusion. leave a space throughout underthe major element excepting at the point where it rests on the centralpart of the minor element, whereby when vthe major element sags duringfusion all the air will be automatically expelled from beneaththe majorelement and the minor element and block vand thus prevent any bubblesbeing formed in the fused surfaces of the Likewise the major elemententirely covers the minor element and protects it from dust and foreignparticles.

The next step in the process is to fuse said elements together when theparts are assembled as shown in Fig. 3, and their condition after fusingis illustrated in Fig. 4. The sagging of the major element causes itsmarginA to move down over and surround the piece l5 whereby said pieceis pushed up into said major portion and the major element comes downflat on the blockat all other points and at the same time that it comesdown in fusion contact with the minor element. This prevents any bendingof the major element thou hout its major surface and the onl bendingthereof that takes place is the s ight sag necessary for its to envelopthe curved surface of the minor element. This makes a fused lens of fineuality. The fused blank is illustrated in ig. 5; an'd thereafter theblank is finished so as to produce a lens substantially as shown in Fi6.

gi different means for holding the major This will finished lens.

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element is shown in Fig. 7 where there is a sprlng clamp 1G with one armresting on the top of the major element andthe other armresting in agroove 17 in the bottom of the block 13. The arm 16 may act as a springand the eect of such holding means is to hold the major element in placeon the minor element and block so that the Inajor surface of the majorelement will not contact with the block prior to fusionbut will be heldapart substantially as shown in Fig. 3 by the piece 15. With the partsmounted in assembly as shown in Fig. 7, prior to fusion, it is obviousthat the major element will sag down into fusion contact, as shown inFig. 8, when subjected to the proper temperature.

The surface of the minor element adjacent to the fusing block should beaccurately surfaced to exactly the same curvature of the block, so thebutton will not warp under heat. Also the wedge 15 might be of glass ofa lower melting point than the glass elements.

In the modified form shown in Fig. 9, the proc-ess is adapted for usewhen the countersink is' in the'convex side of the major element 10.Then the block 13 must be concave.

The invention claimed is:

1. ln the process of making fused multifocal 'lenses wherein there is amajor element with a countersink and a minor element to be fusedtherein, placing the minor element on a block having a curvatureapproximately that of the curvature of the major element and with thecurvature of the minor element extending upward, superimposing the majorelement on said minor element with a 'countersink resting substantiallyon the center of the minor element, mechanically holding said majorelement on the minor element and block so that the major element willnot engage the block preliminary to fusion, and thereafter fusing saidelements, whereby the major element will, during the fusing, .sag downon the minor element and the block. r

2. In the process of making fused multifocal lenses 'as set forth inclaim 1, making the minor element of glass requiring a relatively hightemperature to soften it and giving to it the curvature ultimatelydesired for the curvature of the fused surfaces of the lens whenfinished, making the major element of glass which will soften at a lowertemperature than said minor element and providing therein a countersinkfor the minor element which is of less curvature than the curvature ofthe minor element.

In witness whereof, l have hereunto afiXed my signature.

Lucian w. BUGBEE, JR.

